Overviews Of Systematic Reviews Research Articles

The efficacy and safety of telerehabilitation for patients following total knee arthroplasty: a overviews of systematic reviews

BackgroundStudies evaluating the effectiveness and safety of telerehabilitation in patients undergoing total knee arthroplasty (TKA) have increased. However, the study quality and results differ, systematic reviews are limited. We aimed to synthesise systematic reviews and meta-analyses to assess the effects of telerehabilitation in patients post-TKA.Materials and methodsSystematic reviews and meta-analyses regarding the effectiveness and safety of TKA telerehabilitation were retrieved from eight databases from establishment to 18 December 2022. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2), Risk of Bias in Systematic Reviews (ROBIS) and GRADE system were used to evaluate results, methods, bias and evidence quality.ResultsThirteen systematic reviews and meta-analyses were analysed. The AMSTAR 2 showed low methodological quality in seven studies and very low quality in six. Among the key items, item 2 had been registered on website before systematic review in four reviews. Concerning item 4, did not provide a comprehensive search strategy in 4 reviews. For item 7, none of the reviews provided a list of reasons for excluding an article. For item 9, regarding whether appropriate tools were used to assess the risk of bias of each included study, one review was assessed as ‘partially yes’, one review only included RCTs, and the remainder were assessed as ‘yes’. For item 11, one review did not specify the statistical methods used, and three reviews did not conduct a meta-analysis. For item 13, four reviews considered the risk of bias when interpreting or discussing the study results. For item 15, seven reviews did not evaluate publication bias. The PRISMA scores of the 13 reviews ranged from 17.5 to 26.0. The PRISMA indicated that 69.2% had no protocol registration, 38.5% did not provide other materials and evidence certainty, 23.1% did not provide certainty assessment, 30.8% did not report study bias. According to the ROBIS scale, diferrent domains have diferrent risks in all the reviews.ConclusionTelerehabilitation positively affects walking ability, knee extension and patient costs post-TKA surgery. Regarding the quality of life, patient satisfaction and the WOMAC, telerehabilitation had similar effects to conventional rehabilitation. Owing to the low quality of the studies, these conclusions should be interpreted cautiously, high-quality studies are needed in the future.

Mental health interventions targeting children and young people: A mapping review of interventions, follow-up, and evidence gaps

Background: Young people with mental illness should be offered evidence-based treatments. In 2018, we developed a national evidence portal in Norway providing mental health professionals and others with living evidence summaries. This immense work has been an important contribution to mental health care in Norway but is also a rich data source for exploring the characteristics and evidence gaps of the existing research internationally. At the time of this study, eight overviews of systematic reviews (OoOs) had been published. These addressed treatments for attention deficit / hyperactivity disorder (ADHD), anxiety, depression, bipolar disorder, psychosis, obsessive compulsive disorder (OCD), self-harm and trauma/ post-traumatic stress disorder. The objective of this study was to do a secondary analysis of this evidence to describe the state-of-the art in this field, and to map: treatments evaluated for each patient group and the longest time of follow-uptreatment comparisons evaluated for more than one patient group Methods: We performed a mapping review of the eight OoOs. Data extraction was performed by one author and double-checked by another. All data was entered into Excel. Findings were visualized in descriptive tables and using Sunburst-diagrams. We used statistical thresholds to determine the size of effect and report the associated certainty. Results: We identified 200 treatment comparisons including a wide variety of interventions. Some mental illnesses are treated mostly with pharmacological or combination therapies and others solely with psychological or psychosocial treatments or with more diversity. The evidence supporting most treatments is of low to very low certainty. Ten percent of the comparisons included follow-up assessments beyond 12 months. Cognitive behavioural therapy, dialectic behavioural therapy, physical activity and mindfulness interventions were effective across populations. Conclusions: The evidence supporting treatment of mental illness in young people has important limitations. Future research efforts should address these evidence gaps.

Overviews of Reviews: Concept and Development.

In the last years, overviews of systematic reviews, or umbrella reviews, have seen a dramatic increase in their use. An overview aims to provide a summary of the included reviews and will often examine research questions beyond those addressed in the systematic reviews being synthesised. The purpose of this article is to provide some recommendations on how overviews should be conducted and reported. A literature review was performed to identify relevant papers on both methodological and applied overviews. The current literature recommends carrying out overviews by following similar steps to those of systematic reviews: (a) Defining the overview research question; (b) inclusion and exclusion criteria; (c) literature search; (d) data extraction; (e) assessment of risk of bias and reporting quality; (f) overview results; and (g) reporting the overview. Of special interest is how to address dependencies between the systematic reviews. Overviews allow evidence to be efficiently combined from multiple systematic reviews. This offers the possibility of translating and summarizing large amounts of information. As in primary studies and systematic reviews, conducting and reporting of overviews must meet appropriate quality standards.

Effect of statins on risk and mortality of urologic malignancies: Protocol of an umbrella review.

IntroductionUrologic malignancies are the major causes of morbidity and mortality in men over 40 years old, accounting for more than 20% of all malignant tumors. Several meta-analyses are shown that statin exposure can reduce the morbidity and mortality of various urologic cancers. The adjuvant roles of statin in tumor prevention and anti-tumor activity are now being gradually recognized and have gained attention. Nevertheless, to date, multiple clinical studies and meta-analyses found inconsistent results of their anti-cancer effects. This study aims to evaluate the credibility of the published systematic reviews and meta-analyses that assessed the effects of statin exposure for the incidence and mortality of urologic cancers through an umbrella review.Methods and analysisThe guidance of overviews of systematic reviews reported in the Cochrane Handbook for Systematic Reviews of interventions will be followed while performing and reporting this umbrella review. This project was registered in PROSPERO with the registration number of CRD42020208854. PubMed, Embase and Cochrane Library will be searched for systematic reviews to identify and appraise systematic reviews or meta-analyses of interventional and observational studies examining statin use and the risks of urologic cancer incidence and mortality without language restriction. The search will be carried out on 10 February 2022. Systematic reviews based on qualitative, quantitative or mixed-methods studies will be involved and critically evaluated by two authors using the Assessment of Multiple Systematic Reviews 2 (AMSTAR2, an updated version of AMSTAR) tool. We will determine the level of evidence using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) tool. The summary effect estimates will be calculated using random-effects models. Between- study heterogeneity will be assessed using the I2 statistic. Furthermore, we will also assess the evidence of excess significance bias and evidence of small study effects.Ethics and disseminationEthics approval is not required as we will search and gather data based on the published systematic reviews and meta-analyses. We plan to publish the results of this umbrella review in a peer-reviewed journal and will be presented at a urological disease conference. All the relevant additional data will also be uploaded to the online open access databases.PROSPERO registration numberCRD42020208854.

A new taxonomy was developed for overlap across 'overviews of systematic reviews': A meta-research study of research waste.

Multiple ‘overviews of reviews’ conducted on the same topic (“overlapping overviews”) represent a waste of research resources and can confuse clinicians making decisions amongst competing treatments. We aimed to assess the frequency and characteristics of overlapping overviews. MEDLINE, Epistemonikos and Cochrane Database of Systematic Reviews were searched for overviews that: synthesized reviews of health interventions and conducted systematic searches. Overlap was defined as: duplication of PICO eligibility criteria, and not reported as an update nor a replication. We categorized overview topics according to 22 WHO ICD‐10 medical classifications, overviews as broad or narrow in scope, and overlap as identical, nearly identical, partial, or subsumed. Subsummation was defined as when broad overviews subsumed the populations, interventions and at least one outcome of another overview. Of 541 overviews included, 169 (31%) overlapped across similar PICO, fell within 13 WHO ICD‐10 medical classifications, and 62 topics. 148/169 (88%) overlapping overviews were broad in scope. Fifteen overviews were classified as having nearly identical overlap (9%); 123 partial overlap (73%), and 31 subsumed (18%) others. One third of overviews overlapped in content and a majority covered broad topic areas. A multiplicity of overviews on the same topic adds to the ongoing waste of research resources, time, and effort across medical disciplines. Authors of overviews can use this study and the sample of overviews to identify gaps in the evidence for future analysis, and topics that are already studied, which do not need to be duplicated.

A comparison of two assessment tools used in overviews of systematic reviews: ROBIS versus AMSTAR-2

BackgroundAMSTAR-2 is a 16-item assessment tool to check the quality of a systematic review and establish whether the most important elements are reported. ROBIS is another assessment tool which was designed to evaluate the level of bias present within a systematic review. Our objective was to compare, contrast and establish both inter-rater reliability and usability of both tools as part of two overviews of systematic reviews. Strictly speaking, one tool assesses methodological quality (AMSTAR-2) and the other assesses risk of bias (ROBIS), but there is considerable overlap between the tools in terms of the signalling questions.MethodsThree reviewers independently assessed 31 systematic reviews using both tools. The inter-rater reliability of all sub-sections using each instrument (AMSTAR-2 and ROBIS) was calculated using Gwet’s agreement coefficient (AC1 for unweighted analysis and AC2 for weighted analysis).ResultsThirty-one systematic reviews were included. For AMSTAR-2, the median agreement for all questions was 0.61. Eight of the 16 AMSTAR-2 questions had substantial agreement or higher (> 0.61). For ROBIS, the median agreement for all questions was also 0.61. Eleven of the 24 ROBIS questions had substantial agreement or higher.ConclusionROBIS is an effective tool for assessing risk of bias in systematic reviews and AMSTAR-2 is an effective tool at assessing quality. The median agreement between raters for both tools was identical (0.61). Reviews that included a meta-analysis were easier to rate with ROBIS; however, further developmental work could improve its use in reviews without a formal synthesis. AMSTAR-2 was more straightforward to use; however, more response options would be beneficial.

Bibliometric study of 'overviews of systematic reviews' of health interventions: Evaluation of prevalence, citation and journal impact factor.

Overviews synthesising the results of multiple systematic reviews help inform evidence-based clinical practice. In this first of two companion papers, we evaluate the bibliometrics of overviews, including their prevalence and factors affecting citation rates and journal impact factor (JIF). We searched MEDLINE, Epistemonikos and Cochrane Database of Systematic Reviews (CDSR). We included overviews that: (a) synthesised reviews, (b) conducted a systematic search, (c) had a methods section and (d) examined a healthcare intervention. Multivariable regression was conducted to determine the association between citation density, JIF and six predictor variables. We found 1218 overviews published from 2000 to 2020; the majority (73%) were published in the most recent 5-year period. We extracted a selection of these overviews (n= 541; 44%) dated from 2000 to 2018. The 541 overviews were published in 307 journals; CDSR (8%), PLOS ONE (3%) and Sao Paulo Medical Journal (2%) were the most prevalent. The majority (70%) were published in journals with impact factors between 0.05 and 3.97. We found a mean citation count of 10 overviews per year, published in journals with a mean JIF of 4.4. In multivariable analysis, overviews with a high number of citations and JIFs had more authors, larger sample sizes, were open access and reported the funding source. An eightfold increase in the number of overviews was found between 2009 and 2020. We identified 332 overviews published in 2020, which is equivalent to one overview published per day. Overviews perform above average for the journals in which they publish.

The application of AMSTAR 2 in overviews of systematic reviews shows a need for improvement

Abstract Background Overviews of systematic reviews (SR) summarise and appraise the quality of research relevant for evidence-based decision-making. ‘A Measurement Tool to Assess Systematic Reviews' (AMSTAR 2) is a valid and moderately reliable appraisal instrument with 16 items that can be used to derive the overall confidence rating (OCR). OCR (high, moderate, low or critically low) can be derived based on the original algorithm with 7/9 critical/non-critical items. We aimed to assess the methods for deriving OCR in overviews of SRs of clinical interventions. Methods Our cross-sectional study was conducted using 45 overviews of SRs with at least 20 AMSTAR 2 appraisals selected by two authors from a title/abstract search for ‘AMSTAR 2' in Medline, Epistemonikos and CINAHL in 09/2020. One author coded the data. OCR methods and outcomes were compared using descriptive and univariate statistics. Results The 45 overviews were published in 2018-2020 by 2-16 authors. The overviews appraised on average 44 SRs (range: 20-158). OCRs of 1.412 SRs were derived in 41 overviews (91%). OCR were derived according to the original algorithm (22; 54%), own algorithm (9; 22%), unspecified algorithm (9; 22%) or AMSTAR 2 website (1; 2%). The OCR were high (190; 13%), moderate (182; 13%), low (267, 19%) or critically low (773; 55%). The original algorithm was more likely to generate the critically low+low ratings than either own algorithms (OR = 2.28, 95% CI [1.66-3.13]) or unclear algorithms (OR = 3.78 [2.81-5.09]). Conclusions High quality SRs are needed for making public health decisions. AMSTAR 2 assigns mostly low and critically low OCR to SRs in various clinical areas. These SRs should not be relied on as a source of accurate evidence. Furthermore, our results show that SR reporting guidelines need to be better followed and that AMSTAR 2 users should explicitly report their OCR methods. Key messages The methodological quality of the majority of systematic reviews (SRs) in various clinical fields is disappointing, highlighting the requirement for better adherence to reporting guidelines. There is a need for improvement on reporting how AMSTAR 2 is applied in overviews of SRs.

Does TENS Reduce the Intensity of Acute and Chronic Pain? A Comprehensive Appraisal of the Characteristics and Outcomes of 169 Reviews and 49 Meta-Analyses.

Background and Objectives: Uncertainty about the clinical efficacy of transcutaneous electric nerve stimulation (TENS) to alleviate pain spans half a century. There has been no attempt to synthesise the entire body of systematic review evidence. The aim of this comprehensive review was to critically appraise the characteristics and outcomes of systematic reviews evaluating the clinical efficacy of TENS for any type of acute and chronic pain in adults. Materials and Methods: We searched electronic databases for full reports of systematic reviews of studies, overviews of systematic reviews, and hybrid reviews that evaluated the efficacy of TENS for any type of clinical pain in adults. We screened reports against eligibility criteria and extracted data related to the characteristics and outcomes of the review, including effect size estimates. We conducted a descriptive analysis of extracted data. Results: We included 169 reviews consisting of eight overviews, seven hybrid reviews and 154 systematic reviews with 49 meta-analyses. A tally of authors’ conclusions found a tendency toward benefits from TENS in 69/169 reviews, no benefits in 13/169 reviews, and inconclusive evidence in 87/169 reviews. Only three meta-analyses pooled sufficient data to have confidence in the effect size estimate (i.e., pooled analysis of >500 events). Lower pain intensity was found during TENS compared with control for chronic musculoskeletal pain and labour pain, and lower analgesic consumption was found post-surgery during TENS. The appraisal revealed repeated shortcomings in RCTs that have hindered confident judgements about efficacy, resulting in stagnation of evidence. Conclusions: Our appraisal reveals examples of meta-analyses with ‘sufficient data’ demonstrating benefit. There were no examples of meta-analyses with ‘sufficient data’ demonstrating no benefit. Therefore, we recommend that TENS should be considered as a treatment option. The considerable quantity of reviews with ‘insufficient data’ and meaningless findings have clouded the issue of efficacy. We offer solutions to these issues going forward.

Publication practices of sub-Saharan African Cochrane authors: a bibliometric study

IntroductionCochrane Africa (https://africa.cochrane.org/) aims to increase Cochrane reviews addressing high priority questions in sub-Saharan Africa (SSA). Researchers residing in SSA, despite often drawing on Cochrane methods, training or resources, conduct...

Quality appraisal of systematic reviews of interventions for children with cerebral palsy reveals critically low confidence.

To evaluate the methodological quality of recent systematic reviews of interventions for children with cerebral palsy in order to determine the level of confidence in the reviews' conclusions. A comprehensive search of 22 databases identified eligible systematic reviews with and without meta-analysis published worldwide from 2015 to 2019. We independently extracted data and used A Measurement Tool to Assess Systematic Reviews-2 (AMSTAR-2) to appraise methodological quality. Eighty-three systematic reviews met strict eligibility criteria. Most were from Europe and Latin America and reported on rehabilitative interventions. AMSTAR-2 appraisal found critically low confidence in 88% (n=73) because of multiple and varied deficiencies. Only 7% (n=6) had no AMSTAR-2 critical domain deficiency. The number of systematic reviews increased fivefold from 2015 to 2019; however, quality did not improve over time. Most of these systematic reviews are considered unreliable according to AMSTAR-2. Current recommendations for treating children with CP based on these flawed systematic reviews need re-evaluation. Findings are comparable to reports from other areas of medicine, despite the general perception that systematic reviews are high-level evidence. The required use of current widely accepted guidance for conducting and reporting systematic reviews by authors, peer reviewers, and editors is critical to ensure reliable, unbiased, and transparent systematic reviews. What this paper adds Confidence was critically low in the conclusions of 88% of systematic reviews about interventions for children with cerebral palsy (CP). Quality issues in the sample were not limited to systematic reviews of non-randomized trials, or to those about certain populations of CP or interventions. The inclusion of meta-analysis did not improve the level of confidence in these systematic reviews. Numbers of systematic reviews on this topic increased over the 5 search years but their methodological quality did not improve.

Codeine for Acute Dental Pain and Acute Pain Related to Dental Procedures


 Two overviews of systematic reviews, 4 systematic reviews, and 9 randomized controlled trials were identified comparing codeine or codeine combination drugs with placebo and/or other drugs in the management of acute dental pain.
 As compared to placebo, codeine was generally shown to offer a benefit to patients experiencing acute dental pain.
 When compared to other drugs and/or drug combinations — particularly those that were acetaminophen- or ibuprofen-based — codeine generally was not found to be as clinically effective for the management of acute dental pain, with the potential exception of tooth sensitivity following dental bleaching, where 1 study reported that acetaminophen plus codeine was statistically significantly superior to ibuprofen or placebo.
 Increased adverse events were observed with codeine-containing drugs as compared to other drugs and/or placebo.
 Studies included in this review demonstrated both strengths and limitations, some of which limit the extent to which the findings from these studies were relevant to this report and/or can be generalized.

Tools and tactics for postdischarge medication management interventions.

To identify interventions for organizational pharmacist-leaders and frontline pharmacy staff to optimize peri- and postdischarge medication management. An evidence-based toolkit was systematically constructed on the basis of findings of 3 systematic overviews of systematic reviews. The interventions were reviewed by a technical expert panel and categorized as either tools or tactics. The identified tools are instruments such as diagrams, flow charts, lists, tables, and templates used in performing a distinct operation, whereas identified tactics reflect broader methods (eg, reduced dosing frequency). Tools and tactics were chosen on the basis of their potential to improve postdischarge medication management, with a focus on interventions led by pharmacy staff that may reduce hospital readmissions among older, sicker patients. Overall, 23 tools and 2 tactics were identified. The identified tools include items such as education, text messaging, and phone calls. The tactics identified are dose simplification and monetary incentives. Practical information has also been provided to facilitate implementation. Several tools and tactics are available to optimize peri- and postdischarge medication management. Organizational pharmacist-leaders and frontline pharmacy staff can implement these interventions to improve patient outcomes.

Methods for depicting overlap in overviews of systematic reviews: An introduction to static tabular and graphical displays

Background and ObjectiveTo introduce potential static tabular and graphical techniques for visually presenting overlap between systematic reviews (SRs) included in overviews of systematic reviews (OoSRs). MethodsThe graphical approaches described include Venn and Euler diagrams, as well as matrix-based, node-link, and aggregation-based techniques. We used fundamental concepts of mathematics from set and network theory to develop our novel graphical approaches. The graphical displays were created using R. ResultsOverview authors have the flexibility to choose from a variety of visualizations, depending on the characteristics of their study. If the OoSRs include few SRs, a Venn or an Euler diagram can be used. In case of OoSRs with more SRs, Upset plots, heatmaps, and node-link graphs are more appropriate for visualizing overlapping SRs. Stacked bar plots constitute an aggregation-based technique of illustrating overlap. Strengths and limitations of each graphical approach are presented. ConclusionThe degree of overlap should be explored for the entire study and for specific outcomes of interest. The proposed graphical techniques may assist methodologists and authors in identifying overlap, which in turn may improve validity and transparency in OoSRs. More research is needed to understand which technique would be most useful and easiest to understand.

Correction to: Evidence synthesis relevant to COVID-19: a protocol for multiple systematic reviews and overviews of systematic reviews

Medwave es una revista electrónica revisada por pares y de acceso gratuito, que contiene artículos originales de revisión sobre determinantes clínicos, sociales, políticos y económicos en salud, y de investigación en el ámbito clínico y biomédico. Medwave is an online-only, peer-reviewed and open Access biomedical general journal with original review articles con clinical, social, political and economic determinants of health, and research articles on clinical and biomedical aspects.

Evidence synthesis relevant to COVID-19: a protocol for multiple systematic reviews and overviews of systematic reviews.

The evidence on COVID-19 is being produced at high speed, so it is challenging for decision-makers to keep up. It seems appropriate, then, to put into practice a novel approach able to provide the scientific community and other interested parties with quality evidence that is actionable, and rapidly and efficiently produced. We designed a protocol for multiple parallel systematic reviews and overviews of systematic reviews in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P). We will search for primary studies and systematic reviews that answer different questions related to COVID-19 using both a centralized repository (Epistemonikos database) and a manual search in MEDLINE/PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials. We will also search for literature in several other sources. At least two researchers will independently undertake the selection of studies, data extraction, and assessment of the quality of the included studies. We will synthesize data for each question using meta-analysis, when possible, and we will prepare Summary of Findings tables according to the GRADE approach. All the evidence will be organized in an open platform (L·OVE - Living OVerview of Evidence) that will be continuously updated using artificial intelligence and a broad network of experts. No ethics approval is considered necessary. The results of these articles will be widely disseminated via peer-reviewed publications, social networks, and traditional media, and will be sent to relevant international organizations discussing this topic.

Impact and use of reviews and ‘overviews of reviews’ to inform clinical practice guideline recommendations: protocol for a methods study

IntroductionGuidelines are systematically developed recommendations to assist practitioner and patient decisions about treatments for clinical conditions. High quality and comprehensive systematic reviews and ‘overviews of systematic reviews’ (overviews) represent the...

Development of Evidence-Based Chinese Medicine Clinical Service Recommendations for Cancer Palliative Care Using Delphi Approach Based on the Evidence to Decision Framework.

Objectives: Existing evidence supports the use of certain Chinese medicine (CM) interventions for symptom management among palliative cancer patients. However, evidence-based service recommendations tailored to the local context are needed for CM planning and implementation. In response, we aimed to establish consensus on CM clinical service recommendations for cancer palliative care among Hong Kong experts. Methods: Seven CM interventions showing statistically significant favorable results in existing systematic reviews (SRs) and overviews of SRs were subjected to a GRADE-ADOLOPMENT–based 2-round Delphi survey. Twelve Hong Kong experts in cancer palliative care, including conventionally trained physicians, CM practitioners, and nurses (n = 4 from each category), were invited to participate. Use of the Evidence to Decision framework within the GRADE-ADOLOPMENT approach enabled experts to consider aspects of problem priority, benefits, harms, equity, acceptability, and feasibility when making CM recommendations in cancer palliative care. Results: Three evidence-based CM interventions reached positive consensus as service recommendations, namely: (1) acupuncture for reducing fatigue among palliative cancer patients; (2) acupressure for reducing fatigue among palliative cancer patients; and (3) moxibustion for reducing nausea and vomiting among patients receiving chemotherapy. Median rating of recommendation ranged from 2.5 to 3.0 (interquartile range = 0.00-1.00) on a 4-point Likert-type scale, and the percentage agreement ranged from 83.4% to 91.7%. Conclusions: The GRADE-ADOLOPMENT approach facilitates a consensus-based process of reaching 3 evidence-based CM recommendations for cancer palliative care. Future studies may develop tailored strategies to implement these recommendations in the Hong Kong health system.

Definition of a systematic review used in overviews of systematic reviews, meta-epidemiological studies and textbooks

BackgroundA standard or consensus definition of a systematic review does not exist. Therefore, if there is no definition about a systematic review in secondary studies that analyse them or the definition is too broad, inappropriate studies might be included in such evidence synthesis. The aim of this study was to analyse the definition of a systematic review (SR) in health care literature, elements of the definitions that are used and to propose a starting point for an explicit and non-ambiguous SR definition.MethodsWe included overviews of systematic reviews (OSRs), meta-epidemiological studies and epidemiology textbooks. We extracted the definitions of SRs, as well as the inclusion and exclusion criteria that could indicate which definition of a SR the authors used. We extracted individual elements of SR definitions, categorised and quantified them.ResultsAmong the 535 analysed sources of information, 188 (35%) provided a definition of a SR. The most commonly used reference points for the definitions of SRs were Cochrane and the PRISMA statement. We found 188 different elements of SR definitions and divided them into 14 categories. The highest number of SR definition elements was found in categories related to searching (N = 51), analysis/synthesis (N = 23), overall methods (N = 22), quality/bias/appraisal/validity (N = 22) and aim/question (N = 13). The same five categories were also the most commonly used combination of categories in the SR definitions.ConclusionCurrently used definitions of SRs are vague and ambiguous, often using terms such as clear, explicit and systematic, without further elaboration. In this manuscript we propose a more specific definition of a systematic review, with the ultimate aim of motivating the research community to establish a clear and unambiguous definition of this type of research.

Data extraction methods: an analysis of internal reporting discrepancies in single manuscripts and practical advice

BackgroundData extraction from reports about experimental or observational studies is a crucial methodological step informing evidence syntheses, such as systematic reviews (SRs) and overviews of SRs. Reporting discrepancies were defined as pairs of statements that could not both be true. Authors of SRs and overviews of SRs can encounter reporting discrepancies among multiple sources when extracting data—a manuscript and a conference abstract, and a manuscript and a clinical trial registry. However, these discrepancies can also be found within a single manuscript published in a scientific journal. ObjectivesHereby, we describe examples of internal reporting discrepancies that can be found in a single source, with the aim of raising awareness among authors of SRs and overviews of SRs about such potential methodological issues. ConclusionsAuthors of SRs and overviews of SRs should check whether the same information is reported in multiple places within a study and compare that information. Independent data extraction by two reviewers increases the chance of finding discrepancies, if they exist. We provide advice on how to deal with different types of discordances and how to report such discordances when conducting SRs and overviews of SRs.